SI24914A

SI24914A - The device for reducing vibration and noise in the system, comprisingan electric motor with shaded poles

Info

Publication number: SI24914A
Application number: SI201600114A
Authority: SI
Inventors: Tadej KRANJC; BlaĹľ KRANJC
Original assignee: ebm-papst Slovenija d.o.o.
Priority date: 2016-04-22
Filing date: 2016-04-22
Publication date: 2016-07-29

Abstract

Predlagani izum se nanaša na področje nižanja vibracij in hrupa pri sistemu, obsegaj očem vsaj en elektromotor z zasenčenimi poli, pri čemer vibracija in hrup nastanejo kot posledica iteracije med stresanim magnetnim poljem elektromotorja z zasenčenimi poli in feromagnetno strukturo v neposredni okolici omenjenega elektromotorja, kot na primer vibracija in hrup zaščitne pločevine oz. hrbtne stene pri gospodinjski pečici, ki so posledica delovanja elektromotorja v omenjeni pečici. Po izumu je predvideno, da je v vmesnem prostoru med omenjenim elektromotorjem (8) z zasenčenimi poli in omenjeno feromagnetno strukturo razporejena zaščitna plošča (9) iz feromagnetnega materiala.The present invention relates to the field of lowering the vibrations and noise of the system, comprising at least one electromotor with shaded poles, wherein vibration and noise are generated as a result of an iteration between the shaken magnetic field of an electric motor with shaded poles and a ferromagnetic structure in the immediate vicinity of said electric motor, example of vibration and noise of protective sheet metal. the back walls of the household oven resulting from the operation of an electric motor in said oven. According to the invention, it is envisaged that in the intermediate space between the said electromotor (8) with shaded polyps and said ferromagnetic structure a protective plate (9) from the ferromagnetic material is disposed.

Description

NAPRAVA ZA ZNIŽANJE VIBRACIJ IN HRUPA PRI SISTEMU, OBSEGAJOČEM ELEKTROMOTOR Z ZASENČENIMI POLI [0001] Predlagani izum se nanaša na področje znižanje vibracij in hrupa pri sistemu, obsegajočem vsaj en elektromotor z zasenčenimi poli, pri čemer vibracije in hrup nastanejo kot posledica iteracije med stresanim magnetnim poljem elektromotorja z zasenčenimi poli in strukturo iz feromagnetne kovine v neposredni okolici omenjenega elektromotorja, kot na primer vibracije in hrup zaščitne pločevine oz. hrbtne stene pri gospodinjski pečici, ki so posledica delovanja elektromotorja v omenjeni pečici.[0001] The present invention relates to the field of vibration and noise reduction in a system comprising at least one electromotor with shaded poles, causing vibration and noise as a result of vibration and noise. the field of an electric motor with shaded poles and a structure made of ferromagnetic metal in the immediate vicinity of said electric motor, such as vibration and noise of the protective sheet or the back walls of the household oven resulting from the operation of the electric motor in said oven.

[0002] Elektromotor z zasenčenimi poli med obratovanjem ustvarja v svoji okolici dinamično stresano magnetno polje. Kadar se v okolici tovrstnega elektromotorja nahaja elastična struktura iz feromagnetne kovine, npr. tanka jeklena pločevina, nanjo delujejo dinamične magnetne sile. Rezultat omenjenih magnetnih sil so vibracije in posledično hrup. Če ima napajalna napetost elektromotorja frekvenco f, se največje amplitude hrupa in vibracij pojavijo pri frekvenci 2*f Vzporedno se pojavijo tudi višji harmoniki frekvence 2*f, to so 4*f, 6*f in podobno. Prijavitelju je znano, da se nekateri proizvajalci naprav z vgrajenimi elektromotorji z zasenčenimi poli na različne načine soočajo z omenjeno problematiko. Vibracije in hrup je mogoče minimizirati z oblikovno optimizacijo feromagnetne strukture v neposredni okolici elektromotorja. Ta rešitev omogoča le delno zmanjšanje hrupa.[0002] A shaded-pole electric motor generates a dynamically shaken magnetic field in its surroundings. When an elastic structure of ferromagnetic metal is located in the vicinity of such an electric motor, e.g. thin sheet steel, dynamic magnetic forces acting on it. The result of these magnetic forces are vibrations and, consequently, noise. If the motor supply voltage has a frequency f, the maximum noise and vibration amplitudes occur at a frequency of 2 * f. It is known to the applicant that some manufacturers of devices with integrated electric motors with shaded poles face these problems in different ways. Vibration and noise can be minimized by design optimization of the ferromagnetic structure in the immediate vicinity of the electric motor. This solution allows only a partial reduction of noise.

[0003] Naloga izuma je ustvariti napravo za znižanje vibracij in hrupa pri sistemu, obsegajočem vsaj en elektromotor z zasenčenimi poli, s katero so na enostaven način odpravljene težave znanih rešitev.[0003] It is an object of the invention to provide a vibration and noise reduction device for a system comprising at least one shaded-pole electric motor which easily eliminates the problems of known solutions.

[0004] Zastavljena naloga je po predlaganem izumu rešena z značilnostmi, podanimi značilnostnem delu 1. patentnega zahtevka. Podrobnosti izuma so razkrite v pripadajočih podzahtevkih. Po predlaganem izumu je med feromagnetno strukturo v neposredni okolici elektromotorja z zasenčenimi poli in omenjenim elektromotorjem razporejena vsaj ena zaščitna plošča iz feromagnetnega materiala. Na dinamične lastnosti zaščitne plošče vplivajo dimenzije, oblika in način pritrditve zaščitne plošče. V splošnem velja, da se pri zaščitni plošči z večjo togostjo, pojavijo manjše deformacije le-te zaradi vpliva dinamičnih sil, ki jih povzroča stresano magnetno polje delujočega elektromotorja. Z namenom minimizacije mehanskih vibracij in hrupa se lastna frekvenca zaščitne plošče ne sme ujemati s frekvencami omenjenih dinamičnih magnetnih sil.[0004] The object of the present invention is solved by the features given in the characteristic part of claim 1. Details of the invention are disclosed in the corresponding sub-claims. According to the present invention, at least one protective plate of ferromagnetic material is arranged between the ferromagnetic structure in the immediate vicinity of the shaded-pole electric motor and said electric motor. The dynamic properties of the protection panel are influenced by the dimensions, shape and method of attachment of the protection panel. In general, with a greater rigidity, smaller deflections occur in the protection plate due to the influence of the dynamic forces caused by the shaking magnetic field of the running electric motor. In order to minimize mechanical vibration and noise, the intrinsic frequency of the protection plate must not match the frequencies of the said dynamic magnetic forces.

[0005] Izum je v nadaljevanju podrobneje predstavljen na osnovi neomejujočega izvedbenega primera in s sklicevanjem na priloženo skico, kjer kaže sl. 1 shematski prikaz gospodinjske pečice v navpičnem prerezu;[0005] The invention is hereinafter described in more detail on the basis of a non-limiting embodiment and with reference to the accompanying drawing, where FIG. 1 is a schematic view of a domestic oven in vertical section;

sl. 2 podrobnost pritrditve elektromotorja;FIG. 2 detail of the attachment of the electric motor;

sl. 3 pogled, z delnim izrezom zaščitne plošče, na gospodinjsko pečico s sl. 2 v smeri puščice III.FIG. 3 is a partial cutout of the hob on the oven of FIG. 2 in the direction of arrow III.

[0006] Izum je dalje podrobneje opisan na izvedbenem primeru, pri katerem je sistem, ki obsega vsaj en elektromotor z zasenčenimi poli, izbran kot gospodinjska pečica. Omenjena gospodinjska pečica obsega ohišje 1 pečice z zaščitno pločevino oz. s hrbtno steno 2 in v omenjenem ohišju 1 razporejeno pečniško komoro 3, v katero se dostopa s strani, ki leži nasproti omenjeni hrbtni steni 2 ohišja. Omenjena pečniška komora 3 obsega obod 4, ki je na svoji prvi strani, obrnjeni k hrbtni steni 2 pečice, zasnovana s hrbtno steno 5 komore, na nasprotnem koncu pa obsega odprtino 6 za dostop v omenjeno komoro 3. V pečniški komori 3 je v območju hrbtne stene 5 komore razporejen ventilator 7, ki je gnan z elektromotorjem 8, razporejenim zunaj komore 3, to je na zunanji strani omenjene stene 5 komore. Omenjeni elektromotor 8 je prednostno izbran kot elektromotor z zasenčenimi poli. Omenjeni elektromotor 8 je pri tem vir dinamičnega stresanega magnetnega polja, medtem ko omenjena hrbtna stena 2 oz. stranice ohišja predstavljajo omenjeno feromagnetno strukturo v neposredni okolici elektromotorja 8.[0006] The invention is further described in an embodiment wherein the system comprising at least one shaded-pole electric motor is selected as a household oven. Said household oven comprises a housing of 1 oven with a protective sheet or. with a back wall 2 and an oven chamber 3 arranged in said housing 1, which is accessed from the side opposite said housing wall 2. Said oven chamber 3 comprises a perimeter 4 which, on its first side, faces the back wall 2 of the oven, is designed with the back wall 5 of the chamber, and at the opposite end comprises an opening 6 for access to said chamber 3. In the oven chamber 3 is in the area a fan wall 7 arranged on the back wall 5 of the chamber, driven by an electric motor 8 arranged outside the chamber 3, i.e. on the outside of said wall 5 of the chamber. Said electric motor 8 is preferably selected as a shaded pole electric motor. Said electric motor 8 is a source of dynamic magnetic field shake, while said back wall 2 or. the sides of the housing represent said ferromagnetic structure in the immediate vicinity of the electric motor 8.

[0007] Po predlaganem izumu je na ohišju elektromotorja 8 razporejena vsaj ena zaščitna plošča 9, ki preprečuje širjenje magnetnega polja v okolico elektromotorja 8. Dalje je po izumu predvideno, da je omenjena zaščitna plošča 9 zasnovana iz feromagnetnega materiala. Še dalje je predvideno, da omenjena zaščitna plošča 9 zavzema obliko mnogokotnika, na primer kvadrata, pravokotnika in podobno, ali krožnice, elipse in podobno ter kombinacijo vsega naštetega. Še dalje je predvideno, daje omenjena zaščitna plošča 9 zasnovana integralno, v enem kosu, ali pa je sestavljena iz več ločenih elementov, na primer na način mreže ali sita. Kadar je zaščitna plošča 9 zasnovana v enem kosu, je zlasti prednostno, če zaščitna plošča 9 obsega vsaj eno skoznjo luknjo, prednostno pa niz skoznjih lukenj 10. Ne glede na to, ali je zaščitna plošča 9 zasnovana s skoznjimi luknjami 10 ali na način mreže, morajo biti dimenzije lukenj 10 izbrane na način, da prispevajo k zmanjšanju širjenja magnetnega polja na hrbtno steno 2 ohišja. Poleg predhodno omenjenega prispevajo omenjene skoznje luknje 10 tudi k izboljšanemu hlajenju elektromotorja 8.[0007] According to the present invention, at least one protective plate 9 is arranged on the housing of the electric motor 8, which prevents the magnetic field from spreading to the surrounding of the electric motor 8. Further, according to the invention, it is provided that said protective plate 9 is made of ferromagnetic material. It is further contemplated that said protective panel 9 takes the form of a polygon, such as a square, a rectangle, and the like, or a circle, ellipses, and the like, and a combination of all of the above. It is further contemplated that said protective panel 9 is designed integrally, in one piece, or consists of several separate elements, for example in the form of a mesh or sieve. When the protective panel 9 is designed in one piece, it is particularly advantageous if the protective panel 9 comprises at least one through hole and preferably a series of through holes 10. Regardless of whether the protective panel 9 is designed through holes 10 or in a mesh manner , the dimensions of the holes 10 must be chosen in such a way as to contribute to reducing the propagation of the magnetic field to the back wall 2 of the housing. In addition to the aforementioned holes, said through holes 10 also contribute to the improved cooling of the electric motor 8.

[0008] Omenjena zaščitna plošča 9 zmanjša magnetne sile na hrbtno steno 2 pečice, s čimer se zmanjša mehanske vibracije le-te. Posledično se ustvari manj hrupa. Uporaba zaščitne plošče 9 vpliva med drugim tudi na karakteristiko elektromotorja 8. Zaradi sorazmerno zahtevnega principa delovanja elektromotorja 8 z zasenčenimi poli je parametre zaščitne plošče 9, ki vplivajo na dinamično stresano magnetno polje v okolici in karakteristike elektromotorja 8, matematično kompleksno popisati, zato so za dimenzioniranje zaščitne plošče 9 uporabljeni eksperimentalni pristopi.Said protection plate 9 reduces the magnetic forces on the back wall 2 of the oven, thereby reducing the mechanical vibration thereof. As a result, less noise is generated. The use of the protective panel 9 affects, among other things, the characteristics of the electric motor 8. Due to the relatively demanding principle of operation of the electric motor 8 with shaded fields, the parameters of the protective panel 9, which affect the dynamic stressed magnetic field in the environment and the characteristics of the electric motor 8, are mathematically complex to enumerate. sizing of the panel 9 experimental approaches used.

[0009] Dimenzije zaščitne plošče 9 morajo biti izbrane tako, da zaščitna plošča 9 pokrije čim večji del stresanega magnetnega polja, ki se širi v okolico elektromotorja 8. Dalje mora biti debelina t zaščitne plošče 9 izbrana tako, da v največji mogoči meri omeji širjenje stresanega magnetnega polja v okolico. Večja ko je debelina t zaščitne plošče 9, manjši je vpliv dinamičnih magnetnih sil na elemente v okolici elektromotorja 8. Po drugi strani pa debelina t zaščitne plošče 9 vpliva tudi na karakteristike elektromotorja z zasenčenimi poli, saj se z večanjem debeline t zaščitne plošče 9 manjša mehanska moč elektromotorja 8. Dimenzije zaščitne plošče 9 vplivajo tudi na odvod toplote z elektromotorja 8, saj se z večanjem površine zaščitne plošče 9 veča tudi konvekcija toplote z elektromotorja 8, kar posledično pomeni manjše segrevanje elektromotorja 8.[0009] The dimensions of the protective panel 9 must be chosen such that the protective panel 9 covers as much of the shaken magnetic field as is propagated into the vicinity of the electric motor 8. Further, the thickness t of the protective panel 9 must be chosen to limit propagation as much as possible. of a shaken magnetic field into the surroundings. The greater the thickness t of the protective panel 9, the smaller the influence of the dynamic magnetic forces on the elements in the vicinity of the electric motor 8. On the other hand, the thickness t of the protective panel 9 also affects the characteristics of the electric motor with shaded poles, as the thickness t of the protective panel 9 decreases. the mechanical power of the electric motor 8. The dimensions of the protection plate 9 also affect the heat dissipation from the electric motor 8, as the surface area of the protection plate 9 increases with the convection of heat from the electric motor 8, which in turn results in a lower heating of the electric motor 8.

[OOOIO] Poleg dimenzij zaščitne plošče 9 je merodajna tudi razdalja med elektromotorjem 8 in zaščitno ploščo 9. Večja ko je razdalja L med elektromotorjem 8 in zaščitno ploščo 9, večja je magnetna sila na hrbtno steno 2 pečice. Po drugi strani pa je vpliv večje omenjene razdalje L na karakteristiko elektromotorja 8 manjši.[OOOIO] In addition to the dimensions of the protective panel 9, the distance between the electric motor 8 and the protective panel 9. The greater the distance L between the electric motor 8 and the protective panel 9, the greater the magnetic force on the back wall 2 of the oven. On the other hand, the influence of the aforementioned distance L on the characteristic of the electric motor 8 is smaller.

[OOOll] Na dinamične lastnosti zaščitne plošče 9 vplivajo dimenzije, oblika in način pritrditve zaščitne plošče 9. V splošnem velja, da so zaradi magnetnih sil pri bolj togi zaščitni plošči nižje amplitude vibracij. Poleg tega je potrebno pri dimenzioniranju plošče zagotoviti, da se lastna frekvenca pritrjene zaščitne plošče 9 ne ujame s frekvencami dinamičnih magnetnih sil.[OOOll] The dynamic properties of the protective panel 9 are affected by the dimensions, shape and method of attachment of the protective panel 9. In general, due to magnetic forces, the vibration amplitudes are lower due to the magnetic forces at the more rigid protective panel. In addition, when dimensioning the plate, it is necessary to ensure that the natural frequency of the attached protective plate 9 does not match the frequencies of dynamic magnetic forces.

[00012] Omenjena vsaj ena zaščitna plošča 9 je po izumu lahko razporejena na vsaj eni strani elektromotorja 8. Zaščitna plošča 9 je lahko razporejena tudi na več straneh okoli elektromotorja 8 sočasno. Izbiroma je elektromotor 8 obdan z zaščitno ploščo 8 z vseh svojih strani. Alternativno je zaščitna plošča 9 lahko zasnovana z ukrivljenimi robovi. Eden od mogočih izvedbenih primerov zaščitne plošče 9 je tudi zasnova, ki na način oklepa obdaja elektromotor 8.[00012] Said at least one protective panel 9 according to the invention may be arranged on at least one side of the electric motor 8. The protective panel 9 may also be arranged on several sides around the electric motor 8 simultaneously. Optionally, the electric motor 8 is surrounded by a protective plate 8 on all its sides. Alternatively, the protective panel 9 may be designed with curved edges. One possible embodiment of the protective panel 9 is also a design that encloses the electric motor 8 in a shielding manner.

[00013] PRIMER: Rešitev je bila praktično testirana na kuhinjski pečici z mešalnim pečniškim ventilatorjem. Zvočni tlak seje merilo v pol-gluhi sobi. Pečica je bila postavljena na 0,8 m visoko podlago. Mikrofon je bil nameščen na višini 1,3 m in v oddaljenosti 1 m od hrbtne stene ohišja pečice. Pri merjenju hrupa pečice je deloval le mešalni pečniški elektromotor. Napajalna napetost je bila 230 VAC, 50 Hz. Izmerjena raven zvočnega tlaka pri 100 Hz je pri kuhinjski pečici brez zaščitne plošče znašala 30 dB(A), skupna raven zvočnega tlaka pa okoli 33,5 dB(A). Po namestitvi zaščitne plošče je bila pri 100 Hz izmerjena raven zvočnega tlaka okoli 20 dB(A), skupna raven zvočnega tlaka pa 28,3 dB(A). Predlagana rešitev je torej znižala raven zvočnega tlaka za okoli 10 dB(A) pri 100 Hz, celotno raven zvočnega tlaka pa za okoli 5,2 dB(A).[00013] EXAMPLE: The solution was practically tested on a kitchen oven with a mixing oven fan. Sound pressure sits benchmark in a semi-deaf room. The oven was placed on a 0.8 m high base. The microphone was installed at a height of 1.3 m and at a distance of 1 m from the back wall of the oven casing. When measuring the oven noise, only the mixing oven electric motor operated. Supply voltage was 230 VAC, 50 Hz. The measured sound pressure level at 100 Hz was 30 dB (A) in a kitchen oven without a hob, and the total sound pressure level was about 33.5 dB (A). After the protection panel was installed, a sound pressure level of about 20 dB (A) was measured at 100 Hz, and the total sound pressure level was 28.3 dB (A). The proposed solution therefore reduced the sound pressure level by about 10 dB (A) at 100 Hz and the total sound pressure level by about 5.2 dB (A).

Claims

Patent claims

A vibration and noise reduction device for a system comprising at least one electromotor with shaded poles, wherein the vibrations and noise are generated as a result of an iteration between shaken magnetic radiation of an electromotor with shaded poles and a ferromagnetic structure in the immediate vicinity of said electric motor, characterized in that in the intermediate space between the said electromotor (8) with shaded polyps and said ferromagnetic structure, a protective plate (9) of the ferromagnetic material is disposed.

Device according to Claim 1, characterized in that said ferromagnetic structure is selected as a protective sheet, a back wall (2) of the oven (l), in particular a household oven.

Device according to any of the preceding claims, characterized in that the protective plate (9) is arranged in the vicinity of the electric motor (8).

Apparatus according to any one of the preceding claims, characterized in that said protective plate (9) is constructed of a ferromagnetic material.

Device according to any one of the preceding claims, characterized in that said protective panel (9) occupies a polygon shape, for example a square, a rectangle and the like, or a circle, an ellipse, and the like, and a combination of the aforementioned.

Device according to any one of the preceding claims, characterized in that said protective panel (9) is designed in one piece.

Device according to claim 6, characterized in that said protective panel (9) comprises at least one through hole, and preferably a series of through holes (10).

Device according to any one of the preceding claims, characterized in that said protective panel (9) is composed of several separate elements, for example in a network or sieve mode.